This invention relates to a blood chemical sensor wherein a dye and hydrogel combination are mounted on an optical fiber. The sensor is of the type described in copending U.S. application Ser. No. 07/419,692, filed Oct. 11, 1989, and in U.S. Pat. No. 4,727,730.
The invention has particular application to a microsized sensor of the type described in application Ser. No. 07/419,692. The sensor is mounted on the tip of an optical fiber of about 0.009 inch in diameter. A dye and hydrogel matrix combination is mounted on the tip of the optical fiber. The dye, when excited by a light beam passing through the optical fiber, will fluoresce and the fluorescence will be reflected back through the optical fiber. When that sensor is inserted into the bloodstream of a patient, blood gases or electrolytes will be absorbed into contact with the dye. The quantity of the particular constituent being examined by the sensor in the blood stream will cause a variation in the intensity of the fluorescence. The type of dye, the carrier in which it is bound, and the wavelength or wavelengths of excitation all can be varied to make the sensor selective to a particular constituent of the blood. Principal among these constituents are O.sub.2, CO.sub.2 and pH.